The obesogenic environment characterized by man-made or modifiable aspects of an individual's surroundings such as access to food sources, physical activity venues, and physical features affecting obesity, represents an understudied area in cancer research with significant potential to reduce the burden of cancer through approaches that improve opportunities within the environment for healthy eating and physical activity. The goal of this proposal is to understand the effects of neighborhood-level obesogenic factors on risks of breast, colorectal, and prostate cancer with careful consideration of individual-level health behaviors and genetic predisposition among African Americans and Latinos. We propose in Aim 1 to quantify the independent and joint effects of neighborhood-level and individual-level obesity-related factors on breast, colorectal, and prostate cancer risk among African Americans and Latinos of the Multiethnic Cohort Study. We will link prospectively collected individual-level data from 82,545 African Americans and Latinos to geocoded census and geographic information systems data to obtain neighborhood-level data on obesogenic factors. Next, we will test the association between baseline neighborhood-level and individual-level obesogenic factors and incidence of breast, colorectal, and prostate cancers. The Multiethnic Cohort constitutes a well-characterized resource, having follow-up information that spans up to 17 years since its inception in 1993. In Aim 2 we will examine the independent and joint effects of change in neighborhood-level obesogenic factors over time and residential moves on breast, colorectal, and prostate cancer risk among African Americans and Latinos. We will focus on neighborhood-level obesogenic factors that change from baseline (i.e. same individual address with neighborhood changes due to redevelopment/neglect) and purposeful residential moves (i.e. change in address) in a prospective analysis of cancer risk. Our final Aim 3 will examine heterogeneity in neighborhood- level obesogenic effects by known obesity, body mass index, and cancer susceptibility loci among African Americans and Latinos. This aim will capitalize on existing genotype data for these variants from our nested case-control studies of breast cancer (cases/controls=1239/1603), colorectal cancer (cases/controls=675/1225), and prostate cancer (cases/controls=2275/2275) among African Americans and Latinos. The strengths of this proposal include: 1) the innovativeness of the research;2) the multi-disciplinary investigative team, 3) the efficient use of existing resources, and 4) the scientific and public health significance, especially in regards to understudied minority populations. The knowledge gained by this study may lead to important insight into the multilevel pathways of breast, colorectal, and prostate cancer development, and applying this information may improve the prevention of these common cancers. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because it aims to understand the effects neighborhood- level obesogenic factors on risks of breast, colorectal, and prostate cancer with careful consideration of individual-level health behaviors and genetic predisposition. This is relevant to the NIH's mission because it utilizes a novel multilevel approach to advance our understanding of the relationship between the obesogenic environment and cancer risk-the application of this knowledge may lead to improved strategies in reducing the burden of cancer.